Orally administered tablets of medications or medical preparations including neutraceuticals or neutraceutical preparations are often bitter or have unpleasant taste and are very difficult and uncomfortable to swallow because of the bitter or unpleasant taste. In order to mask the unpleasant or bitter taste of the tablets and to make the tablets easy and convenient to swallow, they are often covered with a palatable coating or optionally covered with a palatable coating and encapsulated in capsules.
Sauter describes encapsulation of elongated, substantially cylindrical, solid objects within gelatin capsules or coverings comprising pairs of capsule portions. The capsule portions with their open ends are positioned facing towards the ends of the objects and are relatively moved onto the objects into a position in which the open ends of the capsule portions are in abutting but not overlapping relationship with each other. The capsule portions are dried on the objects to reduce the moisture content from about 10% to about 25% when the objects are encapsulated. Thereafter, the drying is continued to shrink the capsule portions into a tight fitting relationship with the objects (U.S. Pat. No. 5,511,361). Sauter also describes encapsulation of cylindrical caplets with gelatin capsule halves, in which the gelatin capsule halves containing a moisture content of 18-20% are introduced over the ends of the caplets in abutting but not overlapping relationship with each other and are subsequently allowed to dry and shrink fit tightly on to the caplets (U.S. Pat. No. 5,609,010).
In both the above prior art teachings, air will get invariably entrapped in the capsules during encapsulation and due to the air pressure developed in the capsules, the capsules may get damaged. Furthermore, the capsules are likely to get deformed during encapsulation due to the moisture content in the capsule portions being high thereby damaging the capsules and/or spoiling the shape and size and aesthetic look of the capsules. Since the moisture content in the capsules is high during encapsulation, the capsules are also not suitable for encapsulation of hygroscopic or hydrophilic tablets. The capsules require drying during encapsulation and also after the encapsulation to ensure a shrink fit on the tablets. This is not only inconvenient and cumbersome to carry out but also requires considerable amount of energy. Besides, the production time is increased and productivity is reduced. On coming into contact with the body fluids in the stomach, the body fluids will enter the capsules through the hairline gap (capillary opening) between the abutting ends of the capsule portions and slowly flow into the capsules. Therefore, the disintegration and dissolution of the tablets will be slow.
Amey et al describe encapsulation of caplets in capsules. Encapsulation comprises filling atleast one capsule part with one or more caplets, wherein the clearance between the capsule part and the caplet is in the range of −0.5 to 0.5 mm. Capsule parts are put together and treated by cold shrinking. Empty capsule parts are either kept after production at humid conditions in the range of about 40 to about 90% relative humidity to retain a moisture content in the range of about 14 to about 19% by weight of the capsule shell or are re-humidified to said moisture content before feeding into a capsule filling machine. The capsule parts are kept under above humid conditions within the filling machine during rectifying and assembling with the caplet having a moisture content in the range of about 0 to about 12% by weight. The encapsulated dosage form is dried at a relative humidity in the range of about 20 to about 40% and a temperature in the range of about 15 to about 60° C. to shrink fit on the caplets (U.S. Pat. No. 6,245,350).
In the case of the above prior art teaching also, air is likely to get trapped in the capsule during encapsulation and the capsule may get damaged. Due to the clearance between the caplets and capsule parts also, the capsule parts may collapse on the caplets and get deformed and damaged. As the moisture content in the capsule portions being high during encapsulation, they are prone to get damaged and/or deformed during encapsulation thereby affecting the shape and size and aesthetic look of the capsules. The capsules are also not suitable for encapsulating hygroscopic tablets because of the high moisture content in the capsule parts. On coming into contact with the body fluids in the stomach, the body fluids will enter the capsules through the hairline gap between the abutting ends of the capsule portions and slowly flow into the capsules thereby slowing down the disintegration and dissolution of the tablets. The capsules require drying after encapsulation to ensure a shrink fit on the tablets. Due to drying energy requirement for encapsulation of the tablets increases. Further the production time increases and productivity reduces. It is also difficult and cumbersome to maintain the humidity conditions required in the above prior art teaching.